The present invention is used in association with work transfer devices which transfer workpieces carried on pallets progressively from station to station in a transfer machine and more particularly to improved pallet locating and clamping mechanisms for use in conjunction with the transfer device.
In a typical automated transfer machine, workpieces are mounted securely on individual pallets which are moved progressively in unison from one work station to another. Each work station is equipped with means for positioning or locating a pallet accurately that has been transferred into the station and for clamping the located pallet securely in the located position. Tool heads on the work stations then advance, perform their respective operations on the workpiece, and then retract preparatory to the next operating cycle of the machine. In practice, after the tool heads have retracted, the clamps are released and transfer bars are engaged with the pallets to lift the latter off the positioning or supporting means and then moved to advance the pallets to the next work station where they are again lowered onto positioning and supporting means and clamped and other machining operations are performed on the workpieces.
The machine operations performed on these workpieces may involve milling, drilling or a variety of other operations all of which require that each workpiece not only be securely held in position during the operation so as to avoid tool breakage but also that successive workpieces be positioned in exactly the same location within the work station so as to insure that the machining operation is accurately performed on the workpiece. Further, as such work transfer machines are generally employed in high volume production lines and may be substantially automatic in operation few, if any, of the work stations will be operator attended. It is therefore extremely important that the locating and clamping mechanisms be extremely reliable in operation. Further, it is also desirable to minimize the moving parts and generally simplify the overall construction of such transfer machines so as to reduce the required maintenance and repair as well as to reduce downtime required to accomplish the maintenance and/or repair. Also, as such work transfer equipment is often subject to extreme adverse environmental operating conditions, it is desirable to avoid complex control equipment as much as possible in the interests of improving reliability as well as reducing the complexity and time required for repairs should an equipment failure be encountered.
Accordingly, the present invention provides an economical and efficient work transfer machine having extremely durable passive locating means and positively acting, mechanically actuated and correlated clamping mechanisms which minimizes the need for auxiliary control equipment while insuring a positively acting, durable and reliable machine requiring a minimum of maintenance. The work transfer machine of the present invention may include any desired number of work stations each of which will include pallet locator and clamping means as well as means for raising and lowering workpiece carrying pallets into position thereon. The pallet locator means includes a plurality of V-blocks secured in position on a supporting base each of which cooperates with mating grooves provided on the pallets to position the workpiece precisely with respect to the tool head as the pallet is lowered into the work station. Clamping members are disposed along two sides of the pallet and are mechanically actuated by and sequence correlated with the pallet transfer mechanism which raises and lowers the pallets into and out of engagement with the locators. The mechanical linkage is designed so as to insure that the pallets has been fully lowered prior to engagement of the clamping members with the pallet as well as to insure that the clamping members are released prior to the raising of the pallet for transfer to the next successive work station. The use of this directly coupled, mechanically actuated clamping mechanism eliminates the need for complex and costly control mechanisms and insures a reliable sequence correlation between pallet movements and engagement of the clamping members. Further, the use of the V-blocks and mating grooves on the pallet provides an economical, reliable, and durable means for locating the pallets which require no moving parts. Also, as the V-blocks provide a relatively large surface area of engagement with the pallets all of which actively assists in locating the pallets, the problems of misalignment of the workpieces caused by wear of the locating mechanism is effectively minimized.
Additional advantages and features of the present invention will become apparent from the following description of the preferred embodiment taken in conjunction with the drawings and appended claims.